1. Field of the Invention
The present invention relates to a device for folding and stacking folded sheet articles.
2. Description of the Related Art
A known apparatus for folding and stacking ⅛ fold sheet articles such as napkins is illustrated schematically in FIGS. 1 and 2. A web 10 of material for forming the napkin is fed to a first folding device 12, i.e., a plow, for making a first fold 13, i.e., a plow fold, along a length of the web. After passing over the plow, the folded web is fed between an anvil roll 14 and a knife roll 16 where it is cut to a length of a napkin. The cut napkin length is then folded along a quarter fold line on a quarter fold roll 18 while the napkin length is held onto the anvil roll 14 by a vacuum. FIG. 3 shows the cut napkin 11 after being folded by the quarter fold roll along the quarter fold line 17. After the quarter fold, the napkin is fed to a ⅛ fold roll 20 and folded along a ⅛ fold line 19 while the napkin 11 is held between the quarter fold roll 18 and the ⅛ fold roll 20. The completely folded napkin 11 is then fed to a stacking section where a required count of napkins are fed to a stack 22 for further packaging such as banding.
The use of vacuum folding techniques for folding sheet articles is disclosed, for example, in U.S. Pat. Nos. 1,974,149 and 3,689,061, the entire contents of which are incorporated herein by reference.
As shown at the bottom of FIG. 5, the fold 13 is not made in the center of the web 10. Accordingly, the stack of napkins is more dense on the left side of the stack because of the nature of the plow fold 13. Additionally, even if the fold is made at the center of the web, an edge of the napkin with a fold will be thicker than an edge without a fold. If the napkins are stacked so that their folds lie next to one another, one edge of a stack of folded napkins is significantly thicker or more dense than another edge of the stack of folded napkins which has no folds, thereby making it difficult to handle the stack of folded napkins during subsequent operations, such as packaging.